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(11) | EP 3 040 142 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | SINTERED PULLEY |
| (57) The present invention relates to a sintered pulley (1) for a crankshaft (3) of an
internal combustion engine, the pulley (1) comprising a body (2) of a metal alloy,
the body (2) being substantially annular and provided with a first face of contact
(10) with the crankshaft (3), a second face of contact (11) with a securing element
(4), and a concentric hole (12) for association of the pulley (1) with the crankshaft
(3), the pulley comprising, on the second face of contact (11), a region (13) substantially
adjacent to the hole (12) and point of contact with the securing element (4), the
region (13) being provided with a density of between 7.3 and 7.5 g/cm3 such as to ensure great wear resistance, preventing possible deformations generated
from the compaction of the material of the pulley (1), preventing the emergence of
play in the securing of the pulley (1). |
[0001] The present invention relates to a sintered pulley for a crankshaft of an internal combustion engine, the pulley comprising a densified area, that is to say a region of greater density in relation to the initial density of the pulley.
Description of the state of the art
[0002] Internal combustion engines are energy transformation mechanisms utilized by the vast majority of motor vehicles, basically comprising two principal parts: one or more heads and the engine block. The combustion chambers are located in the base of the head(s) (in Diesel engines in general the combustion chambers are in the piston heads) and the cylinders and the cranked shaft assembly or crankshaft assembly are located in the engine block.
[0003] The crankshaft is a fundamental part in the operation of combustion engines, being responsible for transforming the energy generated by the combustion of the air/fuel mixture into torque. Also known as a cranked shaft, the crankshaft is associated with the connecting rods coupled to the pistons, and transmits the moment generated to the other components connected to the extremities of the shaft thereof.
[0004] At one extremity of the shaft of the crankshaft there is located the flywheel of the engine, associated with the gearbox. At the other extremity of the shaft there is a pulley responsible for causing the rotation of diverse devices, principally lubrication devices, such as for example hydraulic steering pump, air conditioning pump, water pump, etc.
[0005] The pulley utilized on the crankshaft is manufactured by a sintering process and mounted upon the extremity of the shaft by means of a bolt, applying a force required to maintain the assembly secured during the entire working period of the engine. When the bolt is in a system with vibration a deformation may be occasioned on the face of contact of the pulley with the bolt, there occurring compaction of the pulley. This deformation, consequent upon the compaction of the material of the pulley, results in play between the pulley and the bolt, the utilization being necessary of a washer positioned between the pulley and the bolt, normally composed of a conventional steel material comprising a density greater than that of the density of the pulley, eliminating the possibility of compaction of the material.
[0006] However, the use of washers to accommodate the play between the pulley and the bolt is extremely undesirable by virtue of the fact that it increases the quantity of components to be utilized in the assembly of the crankshaft, reducing the productivity of the process, and reducing the quality index of the process, by virtue of the fact that the possibility exists of the assemblies being constructed without the washer.
[0007] Consequent upon all the aforestated, until the present moment there a pulley had not been developed manufactured by a sintering process and provided with a density such as to confer upon the pulley excellent resistance to the effect of compaction of the material composing it, in this manner preventing the deformation of the pulley and the emergence of play of between the pulley and the securing component.
Objects of the invention
[0008] The object of the present invention is the provision of a pulley for use upon a crankshaft of an internal combustion engine, the pulley being manufactured by a sintering process whereof at least one region of the pulley is more densified, that is to say a region provided with greater density in relation to the initial density of the pulley.
[0009] The present invention has moreover as object the provision of a pulley wherein at least the region of the hole, region of contact with a securing means, be provided with a greater density in relation to the remainder of the body of the pulley.
[0010] Furthermore, the present invention has as object the provision of a pulley presenting great resistance to wear in general, being capable of resisting the compaction of the material in the region of contact with the securing means, eliminating deformations and the emergence of play in the securing of the pulley.
Brief description of the invention
[0011] The objects of the present invention are achieved by a sintered pulley for a crankshaft of an internal combustion engine, the pulley comprising a body of a metal alloy, the body being substantially annular and provided with a first face of contact with the crankshaft, a second face of contact with a securing element, and a concentric hole for associating the pulley with the crankshaft, the pulley comprising, on the second face of contact, a region substantially adjacent to the hole being the point of contact with the securing element, the region being provided with a density of between 7.3 and 7.5 g/cm3 (grams per cubic centimeter).
[0012] The objects of the present invention are furthermore achieved by an internal combustion engine comprising at least one pulley as aforedescribed.
Summary description of the drawings
[0013] The present invention shall be described below in greater detail based upon an example of embodiment shown in the drawings. The figures represent:
Figure 1, a perspective view of the pulley of the present invention;
Figure 2, a frontal view of the pulley of the present invention;
Figure 3, a side view of the assembly of crankshaft, pulley and securing element; and
Figure 4, a detailed drawing of the densified region of the pulley of the present invention.
Detailed description of the drawings
[0014] The present invention relates to a sintered pulley 1 for a crankshaft of an internal combustion engine, the pulley 1 comprising a body 2 of a metal alloy, the body 2 being substantially annular provided with a first face of contact 10 with the crankshaft 3, a second face of contact 11 with a securing element 4 and a concentric hole 12 for association of the pulley 1 with the crankshaft 3, the pulley comprising, on the second face of contact 11, a region 13 substantially adjacent to the hole 12 and point of contact with the securing element 4, the region 13 being provided with a density of between 7.3 and 7.5 g/cm3 (grams per cubic centimeter) such as to ensure great wear resistance, preventing possible deformations generated through the compaction of the material of the pulley 1, precluding the emergence of play in the securing of the pulley 1.
[0015] For the correct comprehension of the present invention an initial clarification is necessary in terms of the association of the pulley 1 with the crankshaft 3 and in terms of the sintering process utilized in the manufacture of the pulley 1.
[0016] As explained in the state of the art, crankshaft 3 is a fundamental part in the operation of combustion engines, responsible for transforming the energy generated by the combustion of the air/fuel mixture into torque. Known also as a cranked shaft, the crankshaft 3 is associated with the connecting rods coupled to the pistons and transmits the moment generated to the other components connected to the extremities of the shaft thereof.
[0017] At one extremity of the shaft of the crankshaft 3 is the flywheel of the engine, associated with the gearbox. At another extremity of the shaft there is a pulley 1 responsible for causing the rotation of diverse devices, principally lubrication devices, such as for example hydraulic steering pump, air conditioning pump, water pump, etc.
[0018] The pulley 1 is manufactured by a sintering process and is associable with one of the extremities of the shaft of the crankshaft 3 by means of a securing element, the securing element 4 being preferably, but not obligatorily, a bolt.
[0019] In this manner, the pulley 1 of the present invention comprises a body 2 composed of a metal alloy, the body 2 being substantially annular and provided with a first face of contact 10 maintaining direct contact with one face of the crankshaft 3, and a second face of contact 11 maintaining contact with the securing element 4, in this specific case the securing element 4 being a bolt. The pulley 1 is furthermore provided with a concentric hole 12 for association of the pulley 1 with the crankshaft 3. In this manner there is presented an assembly of crankshaft 3, pulley 1 and securing element 4 (see figures 1 and 2).
[0020] In order to ensure that the aforedescribed assembly is maintained secured during the entire working period of the engine a force is applied to the securing element 4 necessary to ensure such condition. When the securing element 4 is in a system with vibration, in this case the engine in operation, a deformation may occur on the second face of contact 11, there occurring the compaction of a region 13 adjacent to the hole 12 and point of contact with the securing element 4. This deformation, consequent upon the compaction of the material of the pulley 1, results in play between the pulley 1 and the securing element 4.
[0021] Such compaction occurs by virtue of the low density of the material of the pulley 1, originating from a sintering process. The sintering, also known as powder metallurgy, arises from a process wherein powders having, or not, a crystalline preparation are compacted and subsequently subjected to high temperatures, slightly lower than the melting temperature thereof, adhesion of the particles of the powders occurring.
[0022] The pulley 1 of the present invention is composed of a metal alloy with up to 0.5 % by volume of carbon (C), between 1 % and 5 % by volume of copper (Cu), between 1 % and 5 % by volume of nickel (Ni), up to 2 % by volume of molybdenum (Mo), up to 2 % by volume of other materials such as phosphorus (P), manganese (Mn) and sulfur (S), the remainder, approximately 94 % by volume, being of iron (Fe).
[0023] The sintering process presents innumerable advantages compared with other methods of working, such as for example the reduction in, or even the elimination of, reworking of the part produced, the reduction in material losses, the utilization of a great variety of raw materials, the production of parts having good surface finish, facility in the manufacture of complex parts, etc.
[0024] However, in the case of the pulley 1, the material suffers a further compaction resulting from the deformation of the pores of the second face of contact 11, generating play in the securing of the pulley 1 to the crankshaft 3.
[0025] In this sense, the present invention presents, in figures 3 and 4, a pulley 1 comprising a region 13 adjacent to the hole 12 and point of contact with the securing element 4, the region 13 being provided with a density of between 3 % to 5 % greater in relation to the density of the remainder of the pulley 1, attaining approximately the density of conventional steel of 7.85 g/cm3. In this manner, the region 13 comprises a density of between 7.3 and 7.5 g/cm3 (grams per cubic centimeter), whilst the remainder of the pulley 1 comprises a density of between 6.7 and 7.2 g/cm3.
[0026] According to that described in the state of the art, washers are currently utilized to accommodate the play existing between the pulley 1 and the securing element 4, the utilization of washers however being highly undesirable. Such difficulty is avoided through the densification of the region 13 of the pulley 1.
[0027] In summary, the pulley 1 of the present invention presents in the region 13 mechanical properties sufficient to minimize or eliminate the emergence of play through the unplanned compaction of the material of the pulley 1 due to the low density in relation to the conventional steel.
[0028] It is placed on record that diverse tests have been carried out in the sense of encountering the optimum ratio between the quantity of material to be added, in consideration of the total height of the pulley, in the region 13, in the second face of contact 11 and in the diameter of the hole 12, the optimum ratio being encountered as lying between 5 % and 20 %, preferably 10 %, of additional material in the region 13 in relation to the second face of contact 11 and the hole 12.
[0029] Furthermore, with reference to the angles and other geometries of the solution, these serve solely to prevent puncture ruptures, together with preventing the material to be deformed migrating excessively in the direction of the central hole of the part, losing the final dimensions thereof.
[0030] The pulley 1 of the present invention promotes productivity gains, reducing the time for constructing the assembly of the crankshaft 3, pulley 1 and the securing element 4, in addition to moreover reducing the number of components for the construction of the assembly, eliminating the use of washers to accommodate play.
1. Sintered pulley for a crankshaft of an internal combustion engine, the pulley (1)
comprising a body (2) of a metal alloy, the body (2) being substantially annular provided
with a first face of contact (10) with the crankshaft (3), a second face of contact
(11) with a securing element (4), and a concentric hole (12) for association of the
pulley (1) with the crankshaft (3), the pulley (1) characterized in that it comprises, on the second face of contact (11), a region (13) substantially adjacent
to the hole (12), being the point of contact with the securing element (4), the region
(13) being provided with a density of between 7.3 and 7.5 g/cm3 (grams per cubic centimeter).
2. Sintered pulley according to Claim 1, characterized in that the region (13) comprises between 5 % and 20 % of additional material deposited in
relation to the regions of the second face of contact (11) and of the hole (12).
3. Sintered pulley according to Claim 1, characterized in that the region (13) comprises 10 % of additional material deposited in relation to the
regions of the second face of contact (11) and of the hole (12).
4. Sintered pulley according to Claim 1, characterized in that it is composed of up to 0.5 % by volume of carbon (C), of between 1 % and 5 % by
volume of copper (Cu), of between 1 % and 5 % by volume of nickel (Ni), of up to 2
% by volume of molybdenum (Mo), of up to 2 % by volume of other materials such as
phosphorus (P), manganese (Mn) and sulfur (S), the remainder, approximately 94 % by
volume, being of iron (Fe).
5. Sintered pulley according to Claim 1, characterized in that the securing element (4) is a bolt.
6. Internal combustion engine characterized in that it comprises at least one pulley (1) as defined in Claim 1.